add test for "considering explicit config over auto-detected schema"

test/explorer/swagger-explorer.spec.ts

@@ -1179,4 +1179,43 @@ describe('SwaggerExplorer', () => {
       expect(routes).toHaveLength(0);
     });
   });
+
+  describe('should consider explicit config over auto-detected schema', () => {
+    const responsesObject = {
+      '201': {
+        description: 'binary file for download',
+        content: {
+          'application/pdf': {
+            schema: { type: 'string', format: 'binary' }
+          },
+          'image/jpeg': { schema: { type: 'string', format: 'binary' } }
+        }
+      }
+    };
+    @Controller()
+    class FooController {
+      @Get()
+      @ApiOperation({
+        description: 'download file',
+        responses: responsesObject
+      })
+      download() {
+        // handles file download
+      }
+    }
+
+    it('when responses is passed in ApiOperation ', () => {
+      const explorer = new SwaggerExplorer(schemaObjectFactory);
+      const routes = explorer.exploreController(
+        {
+          instance: new FooController(),
+          metatype: FooController
+        } as InstanceWrapper<FooController>,
+        new ApplicationConfig(),
+        'path'
+      );
+
+      expect(routes[0].root.responses).toEqual(responsesObject);
+    });
+  });
 });